Gas turbine engines comprise one or more rotating shafts. As shown in FIG. 1, such a rotating shaft 2 with a centre-line 4 may be held in a bearing 6. The bearing 6 permits the shaft 2 to rotate with respect to a static housing 8 or another shaft. The bearing 6 comprises an inner rotating race 10 and an outer static race 12 with a ball bearing 14 or rollers therebetween.
Typically, there is a support shaft 16 between the bearing 6 and the rotating shaft 2. The inner rotating race 10 of the bearing 6 is secured against an abutment shoulder 20 on the support shaft 16 by virtue of a threaded nut 18. The threaded nut 18 engages a corresponding thread on the support shaft 16. The support shaft 16 is in turn secured to the shaft 2 by virtue of a rotating drive arm 24 and a further threaded nut 22, which engages a corresponding thread on the shaft 2. The further threaded nut 22 holds the rotating drive arm 24 against a portion 16′ of the support shaft 16, which is in turn held against an abutment shoulder 25 on the shaft 2.
In the event that the bearing 6 seizes, there is a risk that the support shaft 16 will stay stationary relative to the housing 8 with the shaft 2 continuing to rotate. Such an occurrence would cause a catastrophic failure to the shaft 2 due to the loads placed upon it. Therefore, in order to reduce the likelihood of this occurring, it has been previously-proposed to place a set of axially disposed splines 26 between the support shaft 16 and the drive arm 24.
However, whilst such splines 26 may perform their intended function, they add a significant amount of weight to the bearing assembly. Furthermore, a bearing assembly with such splines requires a larger forging, casting or starting stock of material and the manufacturer requires the ability to machine internal and external splines. The final components will also have increased weight, due to the inclusion of the splines. The present invention therefore seeks to address these issues.